Pharmaceutical pollution in marine waters and benthic flora of the southern Australian coastline

Environmental context Most human pharmaceutical waste is discharged to the environment. While the presence of pharmaceuticals in freshwater systems is well documented globally, little is known of the impact on marine ecosystems. We measured pharmaceuticals in a marine environment in south-eastern Australia and found pharmaceutical concentrations around 24 000 times higher in benthic flora than in the marine surface waters. We discuss the potential use of seaweeds as biological indicators of pharmaceutical pollution. Rationale Pharmaceuticals are emerging pollutants of concern with a range of adverse consequences for organisms and ecosystems. Their presence in freshwater and estuarine systems has been well documented, but less is known about their prevalence in open ocean, or their uptake by benthic flora. This preliminary survey of the southern Australian coastline sought to measure the concentrations of key pharmaceuticals in both surface waters and benthic flora. Methodology This study used LC-MS/MS to measure the concentration carbamazepine, tramadol and venlafaxine in (1) samples from wastewater treatment plants, (2) ocean surface waters and (3) several species of benthic flora. Surface waters and benthic flora were sampled at two sites near waste water treatment plant (WWTP) discharges, and one site away from any discharge. Results All three pharmaceuticals were detected in surface water samples with their risk assessed (via risk quotient) as medium risk (carbamazepine) or low risk (venlafaxine, tramadol). All three pharmaceuticals were also detected in benthic flora, particularly in brown macroalgae; Tramadol was measured at a maximum of 34.7 ng g−1 in Hormosira banksii, and Venlafaxine was recorded at a maximum of 17.3 ng g−1 in Caulocystis cephalornithos. Discussion The calculated bioconcentration factors suggest the pharmaceutical concentrations in benthic flora were up to ~24 000 times higher than in surrounding surface water. There was also evidence that proximity to WWTP outfalls influenced the levels of pharmaceuticals in benthic flora. The results suggest that the benthic flora may be suitable bioindicators of pharmaceutical contamination and that the potential impacts of pharmaceutical pollutants in marine ecosystems demand further investigation.